In the use of separate ammunition at least one propellant-charge module is dropped into the barrel, followed by the projectile to be fired. A primer cap is then detonated to ignite a primer charge in the charge pack, which in its turn ignites the propellant charge. In the simplest system, the pack simply comprises a bag of the propellant charge provided at one end with the primer or detonating charge.
German published patent specification No. 3,113,406 discloses the use of a rigid cardboard cartridge sleeve instead of a powder bag. These cartridge sleeves contain an end charge and a centrally arranged transmitting charge as well as an augmenting charge and, in order to improve and speed up the ignition, a relatively space-consuming cavity for catching the detonating blast.
A substantial disadvantage of this arrangement is that it is impossible to stack up a number of the cartridge sleeves, since when the stack is too long gas pressures vary excessively within the firing chamber. Furthermore propellant-charge powder subject to brittle failure is destroyed at the base of the shell, which can lead in bad cases to ruining of the shot or even of the weapon. In addition it is possible to put these cartridge sleeves or powder bags into the chamber upside down, leading to misfiring and in extreme cases to damage to the weapon.
Studies of barrel-type weapons using such or similar modular loose-powder propellant charges have showed that especially at charge densities of more than 0.4g/cm.sup.3 irregular gas-pressure curves and therefore nonreproducible trajectories are produced. The cause of this performance lies in the unsatisfactory central burnthrough of the charge pack, which effect is even greater with end-lit charges.